ASTM E966建筑物表面和表面构件气载声音隔离的现场测量标准指南
日期:2012-02-08 11:52
-field testing as in the laboratory, the effect is a weakness at the diffuse field average coincidence frequency that is dependent on material and thickness, often seen around the frequency of 2 500 Hz for drywall and glass specimens. For free field sound coming from one direction only, the coincidence frequency varies with incidence angle and will differ from the diffuse-field value (5). Near or at grazing ( =90) it will be much lower in frequency than the diffuse field (E90 and E336) value, an
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